The accurate measurement of natural gas and other fluids is of critical concern. The measurement of natural gas and other fluids is required with the production, processing, transportation and distribution of natural gas and fluid products from exploration to utilization. The accurate measurement of fluids having a substantial monetary value, for example, natural gas, natural gas liquids, hydrocarbon gases, hydrocarbon liquids, and the like, is essential to the efficient use of the fluids and controlled cost accounting. Specifically, the accurate measurement of fluids is essential for determining accountable custody transfer determinations.
Information storage and retrieval systems are available for utilization and implementation in the invention of the present interactive data entry system and method. For example, U.S. Pat. No. 4,318,184 entitled "Information Storage and Retrieval System and Method" to Millett, et al., issued Mar. 2, 1982, provides a form of hierarchal information groups which is readily usable in the interactive data entry system and method of the present invention. U.S. Pat. No. 4,318,184 is incorporated by reference for all purposes herein.
To accurately measure quantities of valuable fluids, the calculation of flow rate in either mass or volume units is required. It is common practice in the trade to use a meter tube to determine, as accurately as possible, the flow rate in mass or volume units. In its simplest form, a meter tube has a specific inside diameter, a plate holding device such as an orifice fitting or orifice flanges, the straight upstream pipe of equal diameter, and a similar downstream pipe beyond the orifice. The orifice meter utilized within conventional meter tubes is a volumetric meter. The orifice plate creates a differential pressure. The differential pressure created by the orifice meter is developed as a function of the acceleration of the fluid as it passes through the aperture in the plate. The differential pressure measurement in conjunction with density measurement permits a calculation of the flow rate in either mass or volume units. The industrial community employs several units of measurement for flow rate and the many supporting variables. Information concerning the units of measurement for flow rate and the associated variables can be found in A.G.A. Report No. 3-ANSI/API 2530 (1985 ) by the American Gas Association, 1515 Wilson Boulevard, Arlington, Va. 22209, entitled "Orifice Metering of Natural Gas and Other Related Hydrocarbon Fluids." Also, similar information can be found in Flow Measurement Engineering Handbook, by R. W. Miller, published in 1983 by the McGraw-Hill Book Company. In principle, the orifice meter is essentially a mass flow meter based upon the concepts of conservation of mass and conservation of energy. Even with accurate construction and calculation, no two meter tubes give exactly the same readings when the same amount of gas is flowing.
Uncertainties are unavoidable and are caused by the differences between ostensibly duplicate meters. Thus, uncertainty limits are specified in regulations. Section 7, A.G.A. Report No. 3-ANSI/API 2530 (1985). It can be readily appreciated that even when the same amount of fluid is flowing, no two orifice meters can be built to give exactly the same readings. Thus, uncertainties are inherent in any calculation of mass flow rate or volume flow rate. For commercial evaluations, the uncertainties must include some allowance for the pressure and temperature measuring devices as well as allowances for the orifice plate. Thus, the commercial accuracy will be less than the accuracy indicated by the tolerance given for the specific orifice meter. Similarly, the exact duplication of orifice meters and orifice plates is not commercially possible. Two duplicate plates made, installed, and operated as nearly as practicable, in accordance with industry standards and specifications, cannot be expected to have exactly the same readings regardless of how many times or how accurately the two meters are tested. These uncertainties are associated with the practically unavoidable individual differences between ostensibly duplicate plates. The uncertainties do not refer to accidental errors of observation, concerning which no general predictions are possible.
As can be appreciated in the art, several forms of flow equations can be utilized in the design of meter tubes. The choice of any particular flow equation remains with the user and the designer. The particular choice of specific flow equations is mandated, by industry criteria as well as by contractual requirements established by practices and traditions with respect to custody transfer, to be made on the basis of a preferred structure and the measurement data available or required for the specific calculation. Thus, a broad spectrum of design, engineering and manufacturing criteria may be applicable for each particular meter tube used in a site specific situation.
The primary consideration in the design of a metering station is sustained accuracy. Many particulars must be considered and evaluated prior to the ultimate design of a meter tube. The manufacture of the meter tube requires detailed specifications and drawings. In addition to the flow characteristics, the meter tube must be designed for ease of maintenance, repair and service in the piping system to provide accuracy, accessibility, safety and work space for operation. Typically, the desired features of the meter tube are combined into a piping structure with an adequate foundation and a partial or complete shelter arranged to fit the particular sight. Further, the station is designed to require a minimum of piping alterations since the capacity requirements of the particular station may change.
There exists basic physical parameters and industry restraints that must be considered in the design, manufacture and use of meter tubes. Important design factors to be considered are choosing the meter tube size and orifice size necessary for the flow volume, selecting proper materials for the operating pressures involved, selecting the correct length of the meter tube to meet industry and/or code standards and recommendations, and the careful inspection of tubes to ascertain that they meet the standards and recommendations.
Determining the accurate size of a meter tube and the associated orifice for a specific application is critical. The size of a meter tube and orifice can be determined from data published by the American Gas Association, the American Society of Mechanical Engineers and from other fluid meter handbooks. The .beta.-ratio is a critical factor for determining the correct meter tube and associated orifice. The .beta.-ratio is defined as the orifice-to-pipe diameter ratio. Typically to obtain the highest flow accuracy, the .beta.-ratio should be limited to a minimum of 0.15 and a maximum of 0.70 for flange taps. Within the range of .beta.-ratios of 0.15 to 0.70, the accuracy of the coefficient is approximately 0.5%. Within the .beta.-ratio ranges of 0.10 to 0.15 and from 0.70 to 0.75, the accuracy of the coefficient is approximately 1%. The .beta.-ratio constrains the selection of pipe size. The minimum length of meter tube required varies with the .beta.-ratio. The higher the .beta.-ratio the longer the requirement for the length of the meter tube. Meter tube lengths are guided by industry restraints and the practical experience of the designing engineer. Industry restraints are particularly used in the following situations: (1) two bends or elbows, not in the same plane, precede the meter tube; (2) two bends or elbows, in the same plane, precede the meter tube; (3) a partially closed gate or plug valve precedes the meter tube; (4) a concentric reducer precedes the meter tube.
Also, the use of straightening vanes may be required. In determining whether or not straightening vanes are required, each individual meter tube design may have a different set of conditions. For example, the governing factor may not always be the nearest fitting on the inlet end of the meter tube. Therefore, it has been impractical to set up specifications that would suit all conditions. The primary consideration with respect to straightening vanes is the consideration to minimize flow disturbance at the orifice plate from any upstream fitting or fittings.
Further, the maximum allowable working pressures for complete meter tube assemblies is dependent on the maximum allowable working pressures of the pipe, the flanges, the orifice fitting and the valves that make up the assembly.
In designing a typical meter tube system, numerous components must be evaluated and selected according to the sight specific criteria where the meter tube will be used. For example, typical criteria required to be evaluated in the design, engineering and manufacture of a meter tube are: (1) type of fitting, (2) the branch size, (3) the pressure, (4) the bore, (5) the style of fitting connections, (6) the trim, (7) the type of pipe, (8) the end connections, (9) the .beta.-ratio, (10) the applicable A.G.A. FIGS. 4 through 8, (11) the type of straightening vane, (12) the A.G.A. minimum calculations and (13) the length of the meter tube. In evaluating these and related criteria, an interactive data entry in the area of meter tubes has been indispensable. Even the simplest structure may have restraints or criteria which would be out of the ordinary.
There is, thus a need for an interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes for minimizing the redesign of the meter tube characteristics in the design, the engineering and the manufacturing stages.
It is, therefore, a feature of the present invention to provide a unique interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes. It is a more particular feature of the present invention to provide an interactive data entry system and method for assisting in designing, engineering and manufacturing site specific meter tubes. The interactive data entry system and method utilizes a hierarchal information analysis in the evaluation of and the determination of the appropriate meter tube design.
Another feature of the present invention is to provide an interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes which can be used by a "lay person" having no expertise or prior knowledge concerning the technical information used in designing meter tubes other than the specification of the apparatus which is provided by the end user.
Yet another feature of the present invention is to provide an interactive data entry system and method for the design, engineering and manufacture of meter tubes to provide feasibility testing of customer orders and for identifying problems with customer specifications.
Yet still another feature of the present invention is to provide an interactive data entry system and method for the design, engineering and manufacture of meter tubes which guarantees that the meter tube designed can be manufactured according to general physical principles and industry standards.
Yet still another feature of the present invention is to provide an interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes which shortens the design time and thus improves the profitability of the meter tube.
A further feature of the present invention is to provide an interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes which reduces the plant inventory required based upon the design criteria of standard meter tubes.
Still further a feature of the present invention is to provide an interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes which improves customer service, shortens delivery time and increases productivity.
Yet still another feature of the present invention is to provide an interactive data entry system and method for the design, engineering and manufacture of meter tubes which utilizes the results of continuous functions for automatic and deterministic decision making.
Another feature of the present invention is to provide an interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes for converting customer specifications into manufacturing specifications including bills of material, drawings and the like. More particularly, a feature of the present invention is to improve the accuracy of the bills of material and the drawings.
Yet another feature of the present invention is to provide an interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes to convert batch operations to process operations. More particularly, it is a feature of the present invention to convert from the traditional batch operation technique of order entry, design, engineering and manufacturing to a more continuous, process operation such that a value can be added to the product with respect to the time saved.
Still another feature of the present invention is to provide an interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes for accepting customer inquiries or orders and predetermining a profit by avoiding the redesign of a customer order at each stage during the pre-production process by combining all pre-production operations into one.
Yet still another feature of the present invention is to provide an interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes utilizing personal computers such that productivity gains of as high as 72 to 1 can be obtained.
Yet still another feature of the present invention is to provide an interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes to avoid designs outside the manufacturing facility limitations.
A further feature of the present invention is to provide an interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes utilizing a modular or "phantom" bill of material to reduce the number of parts which must be coordinated thereby reducing the development and deployment time.
Yet still another feature of the present invention is to provide an interactive data entry system and method for the design, engineering and manufacture of meter tubes for providing a design tool and a cost estimating tool for providing accurate quotations to prospective clients.
Another feature of the present invention is to provide an interactive data entry system and method for assisting in the design, engineering and manufacture of meter tubes which is deterministic by acting as though the resultant design and associated characteristics are previously known.
Additional advantages and objects of the invention will be set forth in part in the description which follows, and in part will become apparent from the description, or may be learned by practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instrumentalities, combinations and steps particularly pointed out in the appended claims.